Introduction to Tandem X.25 Capabilities

Glossary
065307 Tandem Computers Incorporated Glossary–5
Guardian 90 operating system. Operating system that runs on a Tandem NonStop system.
half duplex. Method of serial communications in which the data flow between two
points can occur in only one direction at a time.
HDLC. High Layer Data Link Control. A protocol specified by the International
Organization for Standardization (ISO) for bit-synchronous communications.
I-frame. Information frame. Link-level frame containing a packet.
incoming call packet. Packet that the network sends to a remote entity in response to
receiving a call request packet addressed to that entity.
InfoWay. Service providing electronic access to Tandem product information and
account team.
INSTALL. Program that allows a user to load all of the system software from a tape and
create an operating-system image.
Integrity S2. Tandem system that runs the UNIX operating system.
interface. Shared boundary defined by common interconnection characteristics.
International Organization for Standardization (ISO). Organization established to promote
development of standards to facilitate international exchange of goods and services.
invitation-to-clear packet. Sometimes sent as the last data packet or after the last data
packet to request the disconnection of a call, to solve the problem of having a clear
packet overtake a data packet (causing a call to be disconnected before all of the data is
received).
IOP. I/O process. System process that controls input and output, usually to and from
a device.
ISO. See International Organization for Standardization.
ITI protocol. Interactive terminal Interface protocol. For X25AM, it is used by the
X25AM process when an application exchanges data with a remote terminal connected
to an X.25 packet-switching network via a PAD.
LAP. See Link Access Procedure.
LAPB. See Link Access Procedure.
leased line. Telephone line reserved for exclusive (private) use of the leasing customer.
link. Call or transmission path (including all equipment) between a sender and
receiver.
Link Access Procedure and Link Access Procedure in a Balanced System (LAP and LAPB).
Procedures used in a packet-switching network for data interchange across the access
link between a network and the computers, terminals, or other devices. Responsible
for activities involving framing, synchronization control, and error detection. LAP is
not included in the 1988 CCITT Recommendation, and it is not supported by X25AM
C30.08 and later versions. Current versions of X25AM support only LAPB.
link layer. See frame layer.